#include <iostream>
#include <stack>

using namespace std;

class Solution
{
public:
    void push(int node)
    {
        while (!stack2.empty())
        {
            stack1.push(stack2.top());
            stack2.pop();
        }
        stack1.push(node);
    }

    int pop()
    {
        while (!stack1.empty())
        {
            stack2.push(stack1.top());
            stack1.pop();
        }
        int ans = stack2.top();
        stack2.pop();
        return ans;
    }

private:
    stack<int> stack1;
    stack<int> stack2;
};

int main()
{
    Solution s;
    s.push(1);
    s.push(2);
    cout << s.pop() << endl;
    cout << s.pop() << endl;
    return 0;
}